1. Field of the Invention
The present invention relates to a fuse terminal and its manufacturing method and more specifically to a fuse terminal provided with a low fusing point metal at the fused portion thereof.
2. Description of the Prior Art
The same applicant has already proposed a fuse terminal provided with a low fusing point metal at a fused portion of the fuse terminal in Japanese Published Unexamined (Kokai) Utility Model Appli. No. 59-66844. In this application, a recessed seat is formed at the middle portion of a fused portion made of a metal having a large thermal deformation such as bimetal (Ni and Cu); a low fusing point metal piece such as tin (S.sub.n) or lead (P.sub.b) is fitted to the recessed seat; and this low fusing point metal piece is held to the fused portion by bending tabs formed extending from both the side ends of the fused portion around the low fusing point metal piece.
In this prior-art fuse terminal, it is possible to improve the fusing characteristics on the basis of alloy formed due to diffusion of low fusing point metal into the fusible material of the fused portion; that is, it is possible to reduce the lower limit of fusion at the low current range, while preventing the fuse from being melted away by an instantaneous excessive current.
In the prior-art fuse terminal as described above, however, there exists a problem in that the fusing characteristics are not stable. This is because (1) since the low fusing point metal piece is fitted into a recess formed in the fused portion and held thereto by only use of bent tabs, the low fusing point metal piece is not stably brought into tight contact with the fusible material (dispersion in adhesion between the low fusing point metal and the fusible material); and (2) since the low fusing point metal piece (e.g. S.sub.n, P.sub.b, etc.) of rod shape is soft and therefore deformable, it is difficult to form the rod-shaped metal piece accurately into a predetermined length (dispersion in dimensions of the low fusing point metal).
In addition, since it is necessary to form a recessed seat on the surface of the fused portion in order to hold the low fusing point metal piece to the fuse terminal, the number of manufacturing steps increases, thus resulting in an increase in the manufacturing cost.